Baseball data buddy James Gentile did a little more research about first-inning pitch counts, and helped uncover a pretty interesting fact.
When teams are tied at the end of the first inning, the team that threw 10 or more additional pitches in the first inning wound up winning the game only 48 percent of the time. In other words, a 10-pitch lead in first-inning pitch differential is worth a couple of points in winning percentage. This data covered all games that were tied at the end of the first between 2002 and 2012.
Think of it this way: the home team usually wins about 54 percent of the time. Home field advantage is worth four points of winning percentage. Having a 10-pitch differential in the first inning in your favor is worth about two points—half of the home field advantage.
Sounds just a little significant, don’t you think? Here’s a little more breakdown…these are for games tied at the end of the first, grouped by the differential in pitches thrown in the first. The percentage refers to the ultimate winning percentage of the team that threw fewer pitches in the first inning.
1-5 pitches: 50.6% (7,098 games in the sample)
6-10 pitches: 50.0% (3,893 games)
11-15 pitches: 51.9% (1,338 games)
15-20 pitches: 51.8% (334 games)
21+ pitches: 40.9% (just 66 games; you may safely ignore this one)
Many thanks to Bill James for helping us think it through.